<!DOCTYPE html>
<html lang="zh-cn">
    <head>
        <meta charset="UTF-8"/>
        <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
        <title>Document</title>
        <style>
            /*聊天窗口_顶部*/
            .nav{
                display:block;
                position:fixed;
                top:0;
                width:100%;
                height:50px;
                font-size:2rem;
                background-color:#393a3f;
                z-index:99;
            }
            /*聊天窗口_内容*/
            .content{
                display:block;
                position:absolute;
                top:50px;
                bottom:50px;
                width:100%;
                height:auto;
                background-color:#ebebeb;
                overflow-y:scroll;
                -webkit-overflow-scrolling:touch;
            }
            /*聊天窗口_底部*/
            #returnframe{
                display:block;
                position:fixed;
                bottom:0;
                width:100%;
                height:50px;
                background-color:#f4f4f4;
                border-top:1px solid #d8d8d8;
                z-index:99;
            }
        </style>
    </head>
    <body>
        <div class="nav"></div>
        <div class="content"></div>
        <div id="returnframe">
           <input type="text" name="inputframe" class='inputframe'>
           <div class="returnframe_button">发送</div>
        </div>
    </body>
</html>